"""Regression tests for blank user echoes displacing actionable compaction state."""

from __future__ import annotations

from unittest.mock import patch

import pytest

from agent.context_compressor import (
    COMPRESSED_SUMMARY_METADATA_KEY,
    SUMMARY_PREFIX,
    ContextCompressor,
)


@pytest.fixture()
def compressor() -> ContextCompressor:
    with patch(
        "agent.context_compressor.get_model_context_length",
        return_value=100_000,
    ):
        instance = ContextCompressor(
            model="test/model",
            threshold_percent=0.85,
            protect_first_n=2,
            protect_last_n=2,
            quiet_mode=True,
        )
    instance.tail_token_budget = 10
    return instance


def _append_tool_run(messages: list[dict], prefix: str, count: int = 6) -> None:
    for index in range(count):
        call_id = f"{prefix}-{index}"
        messages.extend(
            [
                {
                    "role": "assistant",
                    "content": None,
                    "tool_calls": [
                        {
                            "id": call_id,
                            "function": {"name": "read_file", "arguments": "{}"},
                        }
                    ],
                },
                {
                    "role": "tool",
                    "tool_call_id": call_id,
                    "content": "x" * 400,
                },
            ]
        )


def _compress(compressor: ContextCompressor, messages: list[dict]) -> list[dict]:
    with patch.object(
        compressor,
        "_generate_summary",
        return_value=f"{SUMMARY_PREFIX}\nsummary of older work",
    ):
        return compressor.compress(messages, current_tokens=90_000)


def _assert_no_adjacent_user_roles(messages: list[dict]) -> None:
    for previous, current in zip(messages, messages[1:]):
        assert (previous.get("role"), current.get("role")) != ("user", "user")




def test_leading_blank_without_actionable_user_is_not_removed(compressor):
    messages = [
        {"role": "user", "content": ""},
        {"role": "assistant", "content": "visible reply"},
    ]

    assert compressor._find_last_user_message_idx(messages, 0) == -1
    assert compressor._blank_echo_indices_after(messages, -1) == set()






def test_completion_survives_compaction_verbatim_after_blank_echo(compressor):
    completion = (
        "[ASYNC DELEGATION BATCH COMPLETE — deleg_current]\n"
        "The newest result that must remain actionable."
    )
    messages: list[dict] = [
        {"role": "system", "content": "sys"},
        {"role": "user", "content": "initial request"},
        {"role": "assistant", "content": "initial reply"},
    ]
    messages += [
        {"role": "user", "content": f"older question {index}"}
        if index % 2 == 0
        else {"role": "assistant", "content": f"older reply {index}"}
        for index in range(6)
    ]
    messages += [
        {"role": "user", "content": completion},
        {"role": "user", "content": " \n"},
        {"role": "assistant", "content": "working from the completion"},
    ]
    _append_tool_run(messages, "tail")

    result = _compress(compressor, messages)

    completion_rows = [message for message in result if message.get("content") == completion]
    assert len(completion_rows) == 1
    assert not completion_rows[0].get(COMPRESSED_SUMMARY_METADATA_KEY)
    summary_rows = [
        message for message in result if message.get(COMPRESSED_SUMMARY_METADATA_KEY)
    ]
    assert len(summary_rows) == 1
    assert summary_rows[0].get("role") == "user"
    assert all(not compressor._is_blank_user_turn(message) for message in result)
    _assert_no_adjacent_user_roles(result)

    second_result = _compress(compressor, result)
    second_completion_rows = [
        message for message in second_result if message.get("content") == completion
    ]
    assert len(second_completion_rows) == 1
    assert not second_completion_rows[0].get(COMPRESSED_SUMMARY_METADATA_KEY)


def test_completion_at_compress_start_survives_when_blank_echo_is_compress_end(
    compressor,
):
    completion = "latest actionable completion at the compression boundary"
    messages = [
        {"role": "system", "content": "sys"},
        {"role": "user", "content": "initial request"},
        {"role": "assistant", "content": "initial reply"},
        {"role": "user", "content": completion},
        {"role": "user", "content": ""},
        {
            "role": "assistant",
            "content": None,
            "tool_calls": [
                {
                    "id": "boundary-call",
                    "function": {"name": "read_file", "arguments": "{}"},
                }
            ],
        },
        {"role": "tool", "tool_call_id": "boundary-call", "content": "result"},
        {"role": "assistant", "content": "working from the completion"},
    ]

    with (
        patch.object(compressor, "_protect_head_size", return_value=3),
        patch.object(compressor, "_find_tail_cut_by_tokens", return_value=3),
        patch.object(compressor, "_generate_summary") as generate_summary,
    ):
        result = compressor.compress(messages, current_tokens=90_000)

    completion_rows = [message for message in result if message.get("content") == completion]
    assert len(completion_rows) == 1
    assert not completion_rows[0].get(COMPRESSED_SUMMARY_METADATA_KEY)
    assert not any(
        message.get(COMPRESSED_SUMMARY_METADATA_KEY) for message in result
    )
    assert len(result) == len(messages) - 1
    assert compressor.compression_count == 0
    assert compressor._last_compression_savings_pct == 0.0
    generate_summary.assert_not_called()
    assert any(message.get("tool_call_id") == "boundary-call" for message in result)
    assert result[-1].get("content") == "working from the completion"
    assert [message.get("role") for message in result] == [
        "system",
        "user",
        "assistant",
        "user",
        "assistant",
        "tool",
        "assistant",
    ]
    _assert_no_adjacent_user_roles(result)